ITU-R REPORT BS.464-5 PDF

Introduction

From the outset of broadcasting in band 8 (VHF), the provision of high quality was a key feature and was given further impetus by the introduction of stereo transmissions. Thus. during the planning of these new services, consideration was given primarily to properly installed receiving installations employing roof·mounted antennas where studies had shown some advantage in the use of horizontal polarization.

The advent of the transistor has led to the mass production of cheap portable VHF/FM radio sets of high sensitivity and capable of satisfactory operation from built-in rod antennas. Also. the use of VHF/FM with car radios is increasing. Generally, these newer categories of receivers enable a mass audience to be reached and, although they are not able to derive the fullest benefit from high-quality transmissions, they are used in such numbers that they cannot be ignored by broadcasters. It must also be mentioned that there is generally a continuing increase in demand for receivers giving high.quality reception, including stereo.

Thus fixed home receivers may employ fixed antennas with the advantage of greater gain and directivity than is the case for a car or portable radio antenna which has to be nominally omnidirectional in the horizontal plane.

This Report is intended to provide broadcasters with additional data from which they may more easily choose the most appropriate polarization to use for any new service, according to the individual circumstances.